All applications as of the 1st of May must now support the iPhone 5 resolution.
iPhone 5 Optimization Requirement - Your binary is not optimized for iPhone 5. As of May 1, all new iPhone apps and app updates submitted must support the 4-inch display on iPhone 5. All apps must include a launch image of the appropriate size. Learn more about iPhone 5 support by reviewing the iOS Human Interface Guidelines.
There is a little trick to get your AIR application to use the new resolution, you need to include a new Default image, otherwise you're application will always appear in the iPhone 4's resolution.
This new image must have the following:
640w x 1136h
And make sure you package it with your application.